Natural gas is leaking — sometimes deliberately — from residential gas meters up and down the state of California.

That surprise is buried in state documents, a review by inewsource has found.

The leaks do not mean you are in danger of an explosion. But tiny amounts of natural gas escaping from gas meters not only cost you money, they can be the largest single source of leaks for a utility, as they are for San Diego Gas & Electric.

Renters and owners pay for this gas because utilities are allowed to charge customers for gas that is lost or unaccounted for. The bill for all that lost gas, from meters and otherwise, is about $20 million a year in California.

Dan Thomsen, whose company Building Doctors focuses on energy efficiency, said on about 25 percent of the homes he surveys, he finds a gas leak somewhere.

Sometimes the whiffs of gas even come out by design, from a part of the meter known as the pressure regulator. Every meter has one. It is a little-known fact that they burp off gas to relieve pressure.

“That needs exposing right there,” Thomsen said “By capturing those fumes, we would save a god-awful amount of things that are really, really, bad for the environment.”

Natural gas is the consumer-friendly name for methane, which is attracting more attention because of its significance for climate change. When natural gas is released, it traps heat in the air. It plays this role 84 times more powerfully than the better-known greenhouse gas carbon dioxide, when you compare short-term effects.

Most methane in California comes from livestock and landfills, not industry. But the total natural gas leaked from the gas delivery network in California in 2015 was more than the Aliso Canyon well disaster in Los Angeles. That is enough energy to power 285,000 vehicle trips around the globe at the equator.

A quarter of all the gas leaking out of pipelines and natural gas infrastructure is estimated to be coming out near gas meters.

Those small puffs from the pressure regulator are only a tiny fraction. The California Air Resources Board estimates some 800 times that much is leaking out of pipe joints near the meter. They are not sure exactly where and have contracted to find out.

These estimates are a best guess on the part of the board, based on information it gets from utilities, and on a study done in 1996. The board uses estimates because no one routinely measures leaks at the meter.

San Diego Gas & Electric managers were more comfortable talking about leaks as a safety issue than a climate one.

Pete Zepeda, a gas operations site leader, said the company does not consider the burps from the pressure regulators to be leaks.

“If equipment is functioning normally, that is not a leak,” he said. “It is not something we are being irresponsible over.”

When it comes to actual leaks, they are a high priority for SDG&E, said Scott Hazlett, the utility’s gas distribution training supervisor.

Twenty gas patrollers in specially equipped trucks scour roads in San Diego County where pipelines run underneath, looking for leaks. They do nothing else, Hazlett said. The company also has 120 customer service field employees who respond to calls when someone smells gas, he said.

Some leaks go unfixed

The main emphasis for utility companies has been identifying safety risks, not the threat to climate stability. Leaks that present no safety risk have often gone unfixed from one year to the next. More than 21,000 small leaks statewide were carried over from 2015 to 2016.

One of those could have been the leak Sean Armstrong discovered at the edge of the property he shares with his wife, three children, mother and a tenant in the small city of Arcata in Northern California. During the recession, he said, they planted blueberry bushes on a bare patch in the front yard, adding to a variety of fruit they grow. But the plants died. He planted them again. The new ones died.

Armstrong did not know that circles of dead landscaping can be a sign that natural gas is leaking out underground. On July 13, he noticed a man walking through his yard. It turned out to be a gas company contractor who informed him a leak had been identified on the property a year earlier.

The contractor measured a gas concentration high enough to be flammable, Armstrong said. Soon after, another gas employee arrived. He judged the concentration to be lower, and the situation less urgent.

The leak was not only a scare for the family, it was also a blow. They make a conscious effort to limit their emissions.

“It’s killing me that my methane leak is polluting equal to my total CO2 production, and it’s been going on for an unknown length of time,” Armstrong posted on Facebook on July 14.

Their gas company, Pacific Gas & Electric, fixed the leak this month. The utility confirmed the dates in Armstrong’s story.

“They are going to just continue to release methane gas into the atmosphere year after year after year,” said Virginia Palacios, who was a senior research analyst with the group in Austin, Texas, when she spoke with inewsource.

The group believes the true amount of leaked natural gas may be greater than estimates. In one collaboration with Google Earth Outreach and Colorado State University, it outfitted vehicles with especially sensitive methane sensing equipment.

“We are finding far more leaks than utilities generally find in their systems,” Palacios said.

The Google Earth Outreach teams use equipment that measures methane down to parts per billion. Utility companies, including SDG&E, traditionally look for leaks using equipment that can detect when natural gas in the air reaches parts per million.

When someone smells gas and calls the gas company, the response is prompt. Technicians categorize the leak. Grade 1 leaks pose an actual or potential hazard. They are fixed quickly. Grade 2 leaks are not hazardous at the time they are detected but could become dangerous. These are set for repair. Grade 3 leaks are not expected to become hazardous. These are the ones that have been left for years.

Natural gas remains in the atmosphere, like a molecular warming blanket, for approximately 12 years.

Hazlett, the distribution training supervisor with SDG&E, acknowledged that the equipment the utility uses to detect escaping gas is not the most sensitive on the market. PG&E, on the other hand, has 10 SUVs outfitted with next-generation equipment to spot and fix leaks.

The San Diego utility was ahead by a different measure, however. None of the 21,483 California leaks carried over from 2015 to 2016 was theirs.

“We don’t have any backlog of leaks,” Hazlett said. Not even the leaks they find and grade as 3. “We still attack those the same we attack any other leak,” he said.